safe_robot

A low-level ROS package for the safe operation of robots. Easily setup with a single launch file. The safe_robot_node.py acts as a remapper. Target joint states are passed through several safety checks, if safe then the command is sent to the robot, otherwise they are prevented. Possible checks

• joint position limits
• joint velocity limits
• end-effector/link box limits
• self-collision check

Node

safe_robot_node.py

Subscribed topics

• joint_states/target (sensor_msgs/JointState)

  The target joint state.

Published topics

• joint_states/command (sensor_msgs/JointState or std_msgs/Float64MultiArray)

  The commanded joint state. Note, optionally this can be sent as a sensor_msgs/JointState message or std_msgs/Float64MultiArray.

• robot_safety/status (diagnostic_msgs/DiagnosticStatus)

  Status of the joint state.

• (optional) safe_robot/box_limit/marker (visualization_msgs/Marker)

  Optional, marker that shows the box limit for the end-effectors/links. This is only published when debug-mode is turned on (see below).

Parameters

• ~exotica_xml_filename (string)

  An EXOTica XML filename. This should point to a URDF and SRDF file.

• ~link_xlim (string)

  Two floats separated by a space that specifies the end-effector/link limits in the x-axis for the world frame.

• ~link_ylim (string)

  Two floats separated by a space that specifies the end-effector/link limits in the x-axis for the world frame.

• ~link_zlim (string)

  Two floats separated by a space that specifies the end-effector/link limits in the x-axis for the world frame.

• ~safe_links (string)

  A list of links that should be bound with the box limits, each link name should appear in the URDF or EXOTica XML config file. Every name should be separated by a space.

• ~joint_position_limit_factor (double, default: 0.95, min: 0.0, max: 1.0)

  The joint position limits (from URDF) are multipled by a factor to determine safe operation.

• ~joint_velocity_limit_factor (double, default: 0.95, min: 0.0, max: 1.0)

  The joint velocity limits (from URDF) are multipled by a factor to determine safe operation.

• ~safe_distance (double, min: 0.0)

  Safe distance used in self-collision check calculation.

• ~publish_as_joint_state (bool, default: true)

  When true the commands are published as sensor_msgs/JointState messages, otherwise std_msgs/Float64MultiArray messages are used.

• ~check_joint_position_limits (bool, default: true)

  When true the joint position limits are checked, false otherwise.

• ~check_joint_velocity_limits (bool, default: true)

  When true the joint velocity limits are checked, false otherwise.

• ~check_link_limits (bool, default: true)

  When true the end-effector/link limits listed in ~safe_links (above) are checked, false otherwise.

• ~check_self_collision (bool, default: true)

  When true the target state is checked for self-collisions, false otherwise. This utilizes the functionality of EXOTica.

• ~stop_after_first_fail (bool, default: true)

  When true all future target states are prevented.

• ~debug (bool, default: false)

  When true debug mode is turned on.

• ~joint_name_order (string, default: ordering specified by EXOTica)

  This parameter can be used to specify a joint ordering that is different to that is required by a controller. For example, when a robot accepts std_msgs/Float64MultiArray messages, the ordering of the joint positions is critical. Some controllers accept these in a different order to the given URDF.